Screen for hammer type feed grinders



Oct. 2, 1945. E. M. WETMORE 2,386,021

SCREEN FOR HAMMER TYPE FEED GRINDERS Filed' June 4, 1945 /4 a a uy. I. H44 i6 32 /a a4 9 /0 z l 39 I 39 g g 4/ m! H INVENTOR Ear/2m We fmore:

Patented Oct. 2, 1945 SCREElW FOR HAMMER ma FEED amnans Earnest M.Wetmore', Tonkawa, Okla. Application June 4, 1943, Serial No. 489,637

' (c1. 24 1-'as) mer mill which preferably consists of a base 2 7Claims.

This invention relates to screens and more particularly to bar typescreens for feed grinders, ensilage cutters, and hammer mills, theprincipal object of the present invention being to provide a convenient,economical and highly eflicierit screen. l

Screens are provided in hammer mills to retain the feed being ground inthe mill while it is being reduced, however, the ensilage delivered tothe mill quite often contains twine, fibrous material or the like whichballs up and clogs a mill equipped with a conventional bar orperforated-type of screen. e

Other objects ofthe invention are, therefore, to provide a screen forhammer mills or the like capable of retarding or retaining the feed inthe mill while it is being reduced and not ball up with twine o fibrousmaterial in the feedyto provide a'hammer mill screen with bars havingsharpened forward edges for cutting material likely to clog the mill; toprovide a hammer mill screen with staggered bar segments; to provide ahammer mill screen with bars each having a free end for sheddingmaterial therefrom; to provide a screen in a hammer mill in which themotion of the rotor cooperates with the screen to remove material whichtends to clog the mill; to provide a hammer mill screen with barssloping toward the direction of travel of the material in the milltoexpedite cutting and gradual shedding of material from the bars of thescreen; to provide a hammer mill screen with staggered blades arrangedtransversely ofthe direction of travel of material past the blades; andto provide improved elements and arrangements thereof in a screen of thecharacter and for the purpose noted.

In accomplishing these and other objects of the present invention, Ihave provided improved details of structure, the preferred form of whichis illustrated in the accompanying drawing, wherein:

Fig. 1 is a vertical longitudinal section through a hammer mill providedwith a screen embodying the features of the present invention.

Fig. 2 is a transverse sectional view through the mill showing therelation of the screens thereto, substantially on the line 2-2, Fig. 1.

Fig. 3 is a perspective view of the bar type screen embodying thefeatures of the present invention.

Fig. 4 is an enlarged sectional view through the screen on the line 4-4,Fig. 3.

Fig. 5 is a partial plan view of the screen embodying the features ofthe present invention.

Referring more in detail to the drawing:

I, Fig. 1, designates an ensilage cutter or hamthat supports spaced sidewalls 3 and l, 005-, nected with spaced end walls 5 and 6 to form ahousing enclosing a space 1. The upper ends of the side walls taperupwardly and inwardly as at 8 and'Q. The upper end of the end wall 5 isdirected'angularly inwardly as shown at I ll. The upper end of the endwall 6 is curved inwardly as shown at ll. terminating as at l2. Avertically arranged wall 13. spaced from the end of the wall 6, isconnected to and cooperates with the side walls and end H] of wall 5 toform a discharge outlet [4 for the mill, leading to a conduit (notshown) that may terminate in a suitable hopper or the like.

Mounted on the side and end walls within the space 1 of the mill is asubstantially circularly curved plate l5 connected to the walls 5 and 6,as at and I1, forming the. lower portion of a housing, the upper portionof the housing consisting of a concave screen l8 embodying the principalfeatures of the present invention and mounted in the housing to form acontinuation thereof as later described.

20' and 2|. 2, designate bearings for relatively supporting a driveshaft 22 that extends through suitable aligned openings in the sidewalls 3 and 4 of the mill.

23 designates a rotor which preferably consists of a circular plate 24'mounted concentrically on the shaft 22. Secured to the plate 24 andradially arranged in spaced relation about the shaft 22 are bosses 25 ofsuitable number, depending on the size of the rotor and the duties to beperformed thereby. The bosses 25 are provided with apertures 26, wherebybolts or the like 21 may be extended through said apertures andapertures 28' in hammer blades 29 to pivotally mount said hammer bladeson the rotor. The hammer blades 29 are allowed to pivot freely in onedirection and to points limited by the projecting members 30 on thebosses in the other direction.

The screen [8 preferably includes a rectangular frame 30 consisting ofside members 3| and 32 connected by end members 33 and 34, saidrectangular frame being rolled to an arcuate or concave shape. thecurvature of which is substantially the same as that of the wall l5 ofthe mill housing. Extending laterally into the space 35 between the sidemembers 3| and 32 and sloping therefrom toward the direction of rotationof the rotor are bar segments 3 which preferably extend substantially tothe median arc of the screen or-a point midway between the side members3| and 32. The bars connected member 32.

to and extending laterally from the side member 3| are staggeredrelative to the bars connected to and extending laterally of the sideThe bar members 36 are preferably provided with a bevel 31 on the outerportion of the forward edge to provide a sharpened cutting edge 38thereon. The bars are also preferably provided with a slight twist whichpermits the cutting edge 38 to lie in alignment with the inner surface39 of the side members 3| and 32 of the frame 30, the rear portions ofthe bars being spaced outwardly from the axis of curvatureof the screento provide clearance between the cutter bars and the hammers of therotor, thereby forming clearance behind the cutting edge 38 to expeditethe cutting action thereof. This particular arrangement of blades on thebars will cut material moved by the rotor thereacross.

To further expedite the cutting action of the sharpened edges on thebars and to permit gradual shedding of "material tending to ball upon oradhere to the bars, said bars are provided with a slope from their pointof attachment to the side members 3| and 32 to their inner extremitiestoward the direction of travel of the rotor thereby providing shearingaction of the material moved across said'bars and to permit a gradualshedding or'movement of said material therefrom to permit passagethrough the mill.

The concave screen is supported in the upper portion of the housing bymeans of spaced guide members 6| and 42 on each of the walls 3 and l toprovide a guide slot 43 adapted to receive the side members 3| and 32 ofthe screen, said screen being adapted to be inserted in the slot 44formed by the spacing of the end i2 of the member H and the wall l3 andmoved through the guide until the member 33 engages the end 45 of thecurved portion I of the housing. The screen is held in place by a stop46 closing the slot 44 through which the screen is inserted.

The operation of an ensilage cutter or hammer mill and a screenassociatedtherewithconstructed as described, is as follows:

Ensilage of either dry or wet character, such as green feed, wet cornfodder, and/or grasses,

to be comminuted are applied to the housing of the mill through aconventional feed opening (not shown) to the interior of the chamberformed in the mill by the chamber iorming plate I5. The drive shaft 22for the rotor is rotated in a clockwise direction, Fig. 1, by suitabledriving devices whereby centrifugal force generated in rotating therotor holds the ensilage within the confines of the rotor chamber andagainst the inner face of the chamber forming wall i5, where the hammerblades 29 come into play to finely chop and grind the ensilage intominutely comminuted particles. Centrifugal action of the rotoralsocauses the members 30 to act as fan blades for blowing the comminutedensilage around the housing formed by the plate and out through thescreen l8 into the discharge outlet M for subsequent disposition in ahopper or other collecting device. The larger piecesof the material aredirected against the sharpened edges 38 of the bars to further comminutesame as they pass into the outlet 14. The green feed, corn fodder andthe like usually include twine and hard fibrous material which, whenthrown against the bars 36 by the centrifugal force of the rotor, tendto adhere to said bars and gradually ball up and clog the opening 35 ofsaid screen, therethe rotor due to the sloping of said bars from.

v the side members 3| and 32 to the inner extremities of the bars in thedirection of rotation of the rotor. This movement of the twine and othermaterial provides a shearing action which cuts said material and permitsits discharge from the mill, thereby eliminating anypossible'obstruction, balling up, or clogging of the screen, fromobstructing passage of the cut material therethrough. Even if thematerial caught on the blade of the screen is not cut by movementthereover, it is readily shed from the end 40 of said blade, therebyeliminating any obstructionin the screen.

It is apparent, therefore, that the present invention provides animproved screen for ensilage cutters 0r hammer mills that is convenient,economical, highly eflicient and admirably suited for the accomplishmentof the results for which it is intended, and that it is capable ofretarding or retaining the feed in the mill during grinding thereofwithout danger of ballingup or clogging with twine or other fibrousmaterial in the material being ground.

What I claim and desire to secure by Letter Patent is:

l. In a device of the character described, a housing having an outlet, arotor including hammers rotatable in thehousing for reducing materialtherein, a concave screen covering the housing outlet for retardingmaterial being ground-in the housing, said screen including spacedcurved members, and bars spaced on the curved members and extendinglaterally therefrom in the direction of rotation ,of the rotors andterminating in spaced free ends, the bars on one curved member beingstaggered relative to the bars on the other curved member, said curvedmembers and bars defining openings in the screen for passage of materialground in the housing.

2. In a feed grinder, a rotor including hammers rotatable in the grinderfor reducing material therein, an arcuate member forming a portion ofthe wall of said grinder, said arcuate member including end and curvedside members forming an opening therein, and bar segments having aknife-like edge extending laterally of the curved side members and intothe opening in the arcuate member for cutting the material movedthereacross by the rotor, said bars on one side member being staggeredrelative to the bars on the other side member and having free endssubstantially at the median arc of the arcuate member.

3. In a device of the character described, a housing having an outlet, arotor including hammers rotatable in the housing for reducing materialtherein, a screen including a frame covering the housing outlet forretarding materials being ground in the housing, bar segments onoperating with the hammers of the rotor for cutting the material in thehousing.

by interfering with the proper passage of the '18 4. In a device of thecharacter described, a

housing having an outlet, a rotor including hammers rotatable in thehousing for reducing material therein, an arcuate screen including aframe covering the housing outlet for retarding materials being groundin the housing, and bar segments on the frame extending laterallythereof and sloping therefrom in the direction of rotation of the rotor,said bar segments on one side member being staggered relative to thebars on the other side member and having free ends substantially at themedian arc of said screen, and having knife-like forward edges andclearance on the rear edges thereof for cooperating with the hammers ofthe rotor in cutting the material in the housing.

5. In a device of the character described, a

housing having an outlet, a rotor rotatable in the I housing, a screencovering the outlet for retarding material being ground in the housing,said screen consisting of a frame including curved side members, and barsegments extending laterally from said side members and slopingtherefrom in the direction of rotation of the rotor, said bars on oneside member being staggered relative to the bars on the other sidemember and terminating substantially at the median are of the screen,said bars each having a forward edge sharpened to expedite cutting ofthe material in the housing.

6. In a device of the character described, a housing having an outlet, arotor rotatable in the housing; a. screen covering the outlet forretarding material being ground in the housing, said screen consistingof a frame including curved side members, and bar segments extendinglaterally therefrom in the direction of rotation of the rotor, said barsterminating substantially at the median arc of the screen and slopingfrom said side members, said bars having a knife-like edge projectingcounter to rotation of said rotor to expedite cutting oi the material inthe housing.

7. In a device of the character described a concave screen for retardingmaterial being ground including a frame, and bars spaced on said frameand arranged in staggered relation. having their inner ends terminatingat substantially the median arc of said frame, said bars having slopingside faces forming knife-like edges projecting in a direction counter tomovement of said material.

EARNEST M. WETMORE.

